Different types of acoustic devices have been used through the years. One type of device is a microphone. In a microelectromechanical system (MEMS) microphone, a MEMS die includes at least one diaphragm and at least one back plate. The MEMS die is supported by a substrate and enclosed by a housing (e.g., a cup or cover with walls). A port may extend through the substrate (for a bottom port device) or through the top of the housing (for a top port device). In any case, sound energy traverses through the port, moves the diaphragm and creates a changing potential of the back plate, which creates an electrical signal. Microphones are deployed in various types of devices such as personal computers or cellular phones.
When operating in different environments, various types of contaminants can infiltrate into the interior of the microphone. For example, water or dirt may infiltrate the interior of the microphone. This is undesirable because the contaminants can damage the components of the microphone. Damage to the components causes performance problems or can cause the microphone to cease to operate.
Various approaches have been attempted to prevent contaminant ingress into microphones. Unfortunately, many of these approaches themselves degrade the performance of the microphone, for example, by introducing unacceptable levels of noise and decreasing the signal-to-noise ratio (SNR).
The problems of previous approaches have resulted in some user dissatisfaction with these previous approaches.
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